encrypt specified attributes in a Set-Cookie response to be stored in a client, then decrypt and forward the Cookie request only to the originator of the Cookie. An attribute in a Cookie is specified as "attribute@host" or "attribute@.domain". In the former case, a cookie generated by a host is encrypted and echoed to host only. In the latter case, a cookie generated by hosts in the domain can be echoed to hosts in the domain. The special string "%a" in cryptKey is substituted by the IP-address of the client. This makes the crypted Cookie be usable only by clients on the host of the IP-address.